We thank Drs Simon and Freidlin for their very important letter. Their simulation identified an oversight in our approach (1). We performed a simulation with a binary outcome and also found substantial bias in the presence of many predictors. Therefore, we can no longer recommend our proposed approach.

To the Editor: We respectfully request a retraction of the Commentary.

Here’s what happened: One of Baker’s research interests is making clinical studies more efficient, JNCI editor Barry Kramer tells Retraction Watch:

He was trying to develop an efficient method of measuring effects and effect sizes of treatments within prognostic subgroups in clinical trials. He proposed a statistical method that required increasing the sample size slightly, but getting a reliable answer about subsets.

Richard Simon, who wrote the letter in response to the commentary, likely read Baker’s commentary as soon as it came out, did the calculations himself, and “worked it out that the method was prone to bias,” Kramer said.

When the JNCI sent Baker Simon’s letter, as per protocol, “as soon as he saw that, he obviously saw that he had made a conceptual error, and he’s the one who spontaneously said, ‘you’re absolutely right,'” Kramer recalled.

“It was very, very, very fast,” said Kramer. Baker is

the type of person who says, ‘if I’m wrong I want to know I’m wrong.’ That’s the way scientists should be.